The subject of this research project is to reconstruct of paleoenvironment during the Middle Pleistocene of the area from central Honshu to Kanto district based on the correlation of wide-spreaded volcanic ashes such as B_1, B_2, and B_3. After the establishment of correlation of stratigraphy used wide-spreaded volcanic ashes as the time marker, the paleoclimate and paleogeomorphological features are reconstruct.Result of the studies, about 10 wide-spreaded volcanis ashes intercalated in the Lower to Middle Pleistocene sediment were correlated from central Honsyu to Kanto district. Some of the horizons interbeded between the wide-spreaded volcanic ashes indicate the warm climate. Especially, the sediment deposited around 0.42 Ma indicate the most warm climate during the Middle pleistocene and correspond to the 11.3 ^<18>0 stage. And regarding on the Lower-Middle Pleistocene boundary also correlated from Boso peninsula to inland basin such as Yatsugatake region and Matsumoto basin.